Filament winding apparatus and method for ceramic matrix composites

ABSTRACT

An apparatus for making a composite article includes a monofilament feed track adapted to carry a spaced array of ceramic monofilament strands, a fiber yarn feed track adapted to carry a spaced array of fiber yarn tows impregnated with a plurality of glass particulates, a mandrel, and a heater assembly. The mandrel is adapted to wind together individual glass-impregnated fiber yarn strands and individual ceramic monofilament strands to form a dual-fiber weave. The heater assembly is adapted to heat at least the glass particulates such that pressure from the wound array of ceramic monofilaments is sufficient to consolidate the glass particulates and the dual-fiber weave into a dual-fiber ceramic matrix composite (CMC).

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application is a divisional of U.S. application Ser. No.15/022,521, filed Mar. 16, 2016 for “FILAMENT WINDING APPARATUS ANDMETHOD FOR CERAMIC MATRIX COMPOSITES” by D. Jarmon and W. Tredway, whichis a 371 of PCT Application No. PCT/US2014/054786, filed Sep. 9, 2014for “FILAMENT WINDING APPARATUS AND METHOD FOR CERAMIC MATRIXCOMPOSITES” by D. Jarmon and W. Tredway, which claims the benefit ofU.S. Provisional Application No. 61/879,905, filed Sep. 19, 2013 for“FILAMENT WINDING APPARATUS AND METHOD FOR CERAMIC MATRIX COMPOSITES” byD. Jarmon and W. Tredway.

BACKGROUND

The described subject matter relates generally to composite materialsand more specifically to methods for manufacturing composite materials.

Because of their high thermal and mechanical performance and relativelylow density, numerous cylindrical or ring-shaped components couldbenefit from the use of Ceramic Matrix Composites (CMCs) in place ofmetals or intermetallics. The high production cost of current CMCs, andparticularly high-density dual-fiber CMCs results in part from multiplelong processing cycles to achieve sufficient densification. This hasseverely limited adoption of temperature resistant CMCs in gas turbineand hypersonic engines.

Currently, two of the primary cost-effective methods of processingdual-fiber hot section ceramic matrix composite (CMC) components arechemical vapor infiltration (CVI) and polymer infiltration and pyrolysis(PIP), either of which can take 20 days or longer to reach “full”consolidation. Another process is glass transfer molding, which isfaster than CVI and PIP, but is also much more expensive and resourceintensive.

SUMMARY

An apparatus for making a composite article includes a monofilament feedtrack adapted to carry a spaced array of ceramic monofilament strands, afiber yarn feed track adapted to carry a spaced array of fiber yarn towsimpregnated with a plurality of glass particulates, a mandrel, and aheater assembly. The mandrel is disposed at an end of the monofilamentfeed track and an end of the fiber yarn feed track. The mandrel isadapted to wind together individual ones of the spaced array ofglass-impregnated fiber yarn tows and individual ones of the array ofceramic monofilament strands to form a dual-fiber weave. The heaterassembly is disposed within or adjacent to the mandrel and is adapted toheat at least the glass particulates such that pressure from the woundarray of glass monofilaments is sufficient to consolidate the glassparticulates and the dual-fiber weave into a dual-fiber ceramic matrixcomposite (CMC).

A method for making a composite article includes collimating andtensioning a plurality of ceramic monofilaments into a spaced array ofceramic monofilament strands. The first spaced array of ceramicmonofilament strands are commingled with a second array of fiber yarntows, at least some of which are impregnated with a plurality of glassparticulates. The commingled first array of ceramic monofilament strandsand second array of fiber yarn tows are heated, thereby softening theplurality of glass particulates. The commingled glass monofilamentstrands and impregnated fiber yarn tows are wound onto a mandrel. Thesoftened glass particulates, the fiber yarn tows, and the monofilamentstrands are consolidated into a dual-fiber ceramic matrix composite(CMC) material.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows an apparatus for making a dual-fiber ceramic matrixcomposite (CMC) article.

FIG. 2A depicts an array of monofilament strands.

FIG. 2B depicts an array of impregnated fiber yarn tows.

FIG. 2C depicts a consolidated dual-fiber CMC article formed using theapparatus of FIG. 1.

FIG. 3 is a flow chart of a method for making a dual-fiber CMC article.

DETAILED DESCRIPTION

FIG. 1 shows filament winding apparatus 10 for making a compositearticle. Apparatus 10 generally includes monofilament feed track 12,fiber yarn feed track 14, mandrel 16, and heater assembly 18.Monofilament feed track 12 is adapted to arrange and carry array 20 ofspaced ceramic monofilaments, while fiber yarn feed track 12 is adaptedto arrange and carry array 22 of spaced fiber yarn tows.

Monofilament feed track 12 has one or more monofilament spools 24 havinga corresponding plurality of ceramic monofilaments 26 being fed tomandrel 16. Each monofilament spool 24 can be provided with anindividual tensioning device (not shown). Collimator 28 is adapted toreceive unspooled ones of ceramic monofilament strands 26 fromcorresponding monofilament spools 24 (via pulleys 30) by separatingunspooled monofilaments 26 into array 20 of spaced ceramic monofilamentstrands (best shown in FIG. 2A). Collimator 28 can be disposed alongmonofilament feed track 12 between the plurality of monofilament spools24 and mandrel 16.

In FIG. 1, fiber yarn feed track 14 includes a plurality of fiber yarnspools 32 having a corresponding plurality of fiber yarn strands 38 alsobeing directed carried toward mandrel 16. Fiber yarn strands 38 can bemultifilament yarn strands which are impregnated with a plurality ofglass particulates to form impregnated fiber yarn tows 34 (best shown inFIG. 2B). Slurry tank 36, disposed along fiber yarn feed track 14between fiber yarn spools 32 and mandrel 16, can be adapted to receiveunspooled fiber yarn strands 38 from fiber yarn spools 32. Pulleys 35can guide strands 38 into and out of slurry tank 36.

Slurry tank 36 can contain solution 40 for impregnating unspooled fiberyarn strands 34. Solution 40 can include a plurality of glassparticulates and a binder suspended in a carrier liquid, resulting inimpregnated fiber yarn tows 34 being fed to mandrel 16. Fiber yarnstrands 38 can include multifilament yarns composed of one or more ofsilicon carbide (SiC) fiber yarn strands, carbon fiber yarn strands, ormixtures thereof. Fiber yarn strands 38 are under light or no tension sothat they can pick up glass particulates when pulled through solution 40in tank 36. The plurality of glass particulates can include at least oneof: borosilicate glass particles, lithium aluminosilicate glassparticles, barium magnesium aluminosilicate glass particles, andmixtures thereof. The binder can be, for example, organic or inorganic,such as colloidal silica. The carrier liquid can be water or an aqueouscomposition.

After arranging monofilaments 26 and impregnated fiber yarn tows 34 intorespective arrays 20, 22, mandrel 16 can be adapted to wind togetherindividual spaced ones of ceramic monofilament strands 26 and fiber yarntows 34 to form a commingled fiber bundle. Mandrel 16 can be disposed atan end of monofilament feed track 12 and an end of fiber yarn feed track14. Array 20 of monofilament fibers are under high tension and lie downon top of array 22 of impregnated yarn tows 34 as both arrays 20, 22 arewound onto rotating mandrel 16.

The dual-fiber weave is heated by heater assembly 18, and consolidatedon mandrel 16 to produce dual-fiber ceramic matrix composite (CMC) ring42. Heater assembly 18 is disposed within or adjacent to the mandrel 16,and is adapted to heat at least impregnated fiber yarn tows 34. Thedegree of heating is such that the glass particulates (shown in FIG. 2B)are softened, and thus respond to pressure from the wound array ofceramic monofilament strands 26. Glass monofilament strands 26 can betensioned by individual monofilament spools 24, which providesconsolidation pressure to form dual-fiber CMC ring 42.

Dual-fiber CMC ring 42 can form at least a portion of a turbine enginecomponent. Example components include a fan containment case, acompressor shroud liner, combustor liners and heat shields, turbinesupport rings, nozzle seals, and acoustic liners. In combination withmonolithic ceramics, dual-fiber CMC ring 42 can also be used inproduction of lightweight curved armor for military and aerospaceapplications.

In certain embodiments, heater assembly 18 includes energy beamgenerator 44 disposed adjacent to mandrel 16. Energy beam generator(e.g., laser generator) 44 is adapted to direct at least one beam 46toward fiber yarn feed track 14, and more specifically, towardimpregnated fiber yarn tows 34. Heater assembly 46 can include,additionally and/or alternatively, resistance heater 47 disposed withinmandrel 16. This is shown schematically as a cutaway into mandrel 16.

To further facilitate formation of CMC ring 42, apparatus 10 can includeadditional optional elements such as dryer 48 and/or burnoff unit 50.Dryer 48, which can be a heat lamp or other apparatus maintainedseparately from heater assembly 46, can remove excess slurry liquid fromimpregnated fiber yarn tows 34 prior to being wound on mandrel 16. Dryer48 also provides heat to bond the glass particulates to each of thefiber yarn strands 38. Burnoff unit 50 can be adapted to burn offancillary fiber sizing which the fiber manufacturer often applies to thefiber yarn strands 38 to simplify handling. Burnoff unit 50 can be acontrolled flame or a furnace. Removal of the ancillary fiber sizingaids in producing a dual-fiber composite with long term durability.

FIG. 2A shows array 20 of spaced ceramic monofilament strands 26. Asnoted with respect to FIG. 1, monofilament array 20 provides bothconsolidation pressure for dual-fiber CMC ring 42, as well as excellentmechanical properties for aircraft and armor applications. Strands 26can include, for example, a plurality of silicon carbide (SiC)monofilament strands.

A nominal diameter of each of the ceramic monofilament strands measuresat least about 100 μm (about 0.0040 inches). Individually tensionedmonofilaments 26 can generate pressures of at least about 430 MPa (about60ksi) as they are pulled on to the rotating mandrel, which issufficient to consolidated selected dual-fiber glass composites such asdual-fiber CMC ring 42 (shown in FIG. 1). In certain embodiments,tensioned monofilaments 26 can generate pressures of at least about 570MPa (about 80 ksi).

Multiple spools of individually tensioned monofilaments 26 can beprovided. The relative number of tensioned monofilaments 26 andcorresponding monofilament spools 24 (shown in FIG. 1) is adjusted toachieve the desired volume percent of monofilament fibers in dual-fiberCMC ring 42. In certain embodiments, the volume percent of monofilamentfibers in the resultant CMC is in the range of about 30% to about 50%.In certain of these embodiments, the volume percent of monofilamentfibers in the resultant CMC is in the range of about 35% to about 45%.The individual monofilaments can be collimated horizontally (viacollimator 16 in FIG. 1) prior to winding on mandrel 16 (also in FIG.1).

FIG. 2B shows array 22 of impregnated fiber yarn tows 34. As shown inFIG. 1, glass particulates can be combined with multifilament yarn fiberstrands 38 along fiber yarn track 14. Yarn fiber strands 38 can bepulled by rotating mandrel 16 through a slurry (e.g., solution 40 inFIG. 1) containing glass particulates, water, and a binder. As long asthey remain under low or no tension, fiber filaments in strands 34 canspread as they travel through the slurry which allows glass particulates52 to distribute evenly. If the yarn is under high tension, it will bepulled into a tight circular tow which will be difficult for the glassparticulates to penetrate. There is also a danger of yarn fiber strands38 breaking under high tension, especially if glass particulates producepoint contact traveling over pulleys.

In certain embodiments, a typical size distribution for the glassparticulates is a nominal 325 mesh. The binder can be organic orinorganic. Inorganic binders do not leave a carbon residue. A suitable,nonlimiting example of an inorganic binder is Ludox® AS-40 colloidalsilica, available commercially from Sigma-Aldrich Company.

After exiting this slurry the yarn passes under a heat lamp to removethe water and the glass particulates bonded to the individual fiberfilaments by the binder. The concentration of glass particulate in theslurry is adjusted to achieve the desired volume percent of glass in theresultant composite. The desired volume percent of glass in theresultant CMC is typically in the range of 35% to 45%.

FIG. 2C shows a section of consolidated dual-fiber CMC ring 42. Heat issupplied to glass particulates (in FIG. 2B) to lower their viscosity.Heat is applied to a point where the pressure from the monofilamentfiber is able to consolidate the glass, yarn, and monofilament into adense dual fiber reinforced CMC which includes monofilaments 26, andfiber yarn strands 38 retained in glass matrix 56.

It can be seen in FIG. 2C that there are substantially more fiber yarntows than glass monofilament strands. A ratio of glass monofilamentstrands to fiber yarn tows can be at least about 8:1. In certainembodiments, the ratio can be at least about 10:1.

FIG. 3 shows steps of method 100 for making a composite article such asdual fiber reinforced CMC ring 42 (shown in FIG. 1). This is a potentialeconomical method of fabricating cylindrical/ring shaped CMC structuresfor engine components, such as for combustor liners, shrouds,containment rings, etc.

Method 100 begins with step 102 in which a plurality of ceramicmonofilaments are collimated into a spaced array of glass monofilamentstrands. In certain embodiments, the ceramic monofilaments includesilicon carbide (SiC) glass monofilaments.

Monofilaments can be provided with a diameter of at least about 100 μm(about 0.0040 inch), and in certain embodiments, at least about 140 μm(about 0.0056 inch). As discussed above, individually tensionedmonofilaments can generate pressures of at least about 430 MPa (about 60ksi) as it is pulled on to the rotating mandrel which is sufficient toconsolidated selected fiber reinforced glass composites. One suitablenon-limiting example of SiC monofilaments is SCS-6 SiC monofilament,available commercially from Specialty Materials, Inc. of Lowell, Mass.

The number of spools is adjusted to achieve the desired volume percentto monofilament fibers in the resultant composite. The desired volumepercent of monofilament fibers in the resultant CMC is typically in therange of 35% to 45%. Each spool of monofilament fiber has an individualtensioning device. Typical devices will be able to control themonofilament tension from 10 grams to 1100 grams of force. Theindividual monofilaments are collimated prior to winding on the mandrel.A typical or average spacing for the monofilament can be about 0.178 mm(about 0.007 in). +/− about 0.051 mm (about 0.002 in)

At step 104, the spaced array of ceramic monofilament strands aretensioned. This can be done in conjunction with or separately fromcollimating step 102. Tensioning the ceramic monofilament strandsprovides consolidation pressure to the heated and impregnated fiber yarntows of step 114, below.

Optional step 106 involves adhering a plurality of glass particulates toat least some of the plurality of fiber yarn tows. In certain optionalembodiments, some or all of the unspooled fiber yarn strands areimpregnated with glass particulates as was shown in FIG. 1. Thusadhering step 106 can include passing at least some of the plurality offiber yarn tows through a slurry of glass particulates and carrierliquid and evaporating the carrier liquid from the fiber yarn tows toform the array of fiber yarn tows. In lieu of step 106, some or all ofthe fiber yarn tows can be impregnated with glass particulatesseparately from embodiments of method 100.

Step 108 includes the interleaving or commingling of monofilament fibersstrands and glass particulate impregnated yarn strands. And as part ofstep 108, the array of glass monofilament strands and the array ofimpregnated fiber yarn tows are commingled with one another to form adual-fiber weave.

Step 110 can include heating the commingled first and second arrays ofmonofilament fibers strands and glass particulate impregnated yarnstrands. At least some of the fiber yarn tows are impregnated with aplurality of glass particulates. The array of fiber yarn tows can beheated (step 110) prior to the winding step (step 112 below) bydirecting an energy beam toward the plurality of fiber yarn tows tosoften the plurality of glass particulates. Alternatively the step ofheating the array of fiber yarn tows comprises during the winding step112, heating a surface on or adjacent to the mandrel to soften theplurality of glass particulates.

At step 112, the commingled arrays of glass monofilament strands andimpregnated fiber yarn tows are wound onto a mandrel, while step 114involves consolidating the glass particulates, the fiber yarn tows, andthe monofilament strands into a dual-fiber ceramic matrix composite(CMC) material. Pressure from the tensioned array of monofilamentstrands (step 104) can act on the fiber yarn tows and the softened glassparticulates (step 110). In certain embodiments, this pressure issufficient to, at least in part, perform consolidating step 114. Incertain of these embodiments, the ceramic monofilament strands can applya pressure of at least about 430 MPa (about 60 ksi) to the array offiber yarn tows and softened glass particulates. In yet certain of theseembodiments, the glass monofilament strands apply a pressure of at leastabout 570 MPa (about 80 ksi) to the array of fiber yarn tows andsoftened glass particulates.

Discussion of Possible Embodiments

The following are non-exclusive descriptions of possible embodiments ofthe present invention.

An apparatus for making a composite article includes a monofilament feedtrack adapted to carry a spaced array of ceramic monofilament strands, afiber yarn feed track adapted to carry a spaced array of fiber yarn towsimpregnated with a plurality of glass particulates, a mandrel, and aheater assembly.

The apparatus of the preceding paragraph can optionally include,additionally and/or alternatively, any one or more of the followingfeatures, configurations and/or additional components:

An apparatus according to an exemplary embodiment of this disclosure,among other possible things, includes the mandrel disposed at an end ofthe monofilament feed track and an end of the fiber yarn feed track. Themandrel is adapted to wind together individual ones of the spaced arrayof glass-impregnated fiber yarn tows and individual ones of the array ofceramic monofilament strands to form a dual-fiber weave. The heaterassembly is disposed within or adjacent to the mandrel and is adapted toheat at least the glass particulates such that pressure from the woundarray of glass monofilaments is sufficient to consolidate the glassparticulates and the dual-fiber weave into a dual-fiber ceramic matrixcomposite (CMC).

A further embodiment of the foregoing apparatus, wherein themonofilament feed track comprises a plurality of monofilament spoolshaving a corresponding plurality of ceramic monofilament strands; and acollimator disposed along the monofilament feed track between theplurality of monofilament spools and the mandrel.

A further embodiment of any of the foregoing apparatus, wherein thecollimator is adapted to receive unspooled ones of the plurality ofceramic monofilament strands from the plurality of correspondingmonofilament spools, and to separate the unspooled ones into the firstspaced array of ceramic monofilament strands.

A further embodiment of any of the foregoing apparatus, wherein theplurality of ceramic monofilament strands comprises a plurality ofsilicon carbide (SiC) ceramic monofilament strands.

A further embodiment of any of the foregoing apparatus, wherein thefiber yarn feed track comprises a plurality of fiber yarn spools havinga corresponding plurality of fiber yarn tows; and a slurry tank disposedalong the fiber yarn feed track between the plurality of fiber yarnspools and the mandrel.

A further embodiment of any of the foregoing apparatus, wherein theslurry tank is adapted to receive unspooled ones of the plurality offiber yarn strands from the plurality of corresponding fiber yarnspools, and to impregnate the unspooled ones with a plurality of glassparticulates contained in the slurry tank.

A further embodiment of any of the foregoing apparatus, wherein theplurality of fiber yarn tows comprises at least one of: a plurality ofsilicon carbide (SiC) fiber yarn strands, a plurality of carbon fiberyarn strands, or mixtures thereof.

A further embodiment of any of the foregoing apparatus, wherein theslurry tank contains a slurry comprising a plurality of glassparticulates and a binder suspended in a carrier liquid.

A further embodiment of any of the foregoing apparatus, wherein theplurality of glass particulates comprises at least one of: borosilicateglass particles, lithium aluminosilicate glass particles, bariummagnesium aluminosilicate particles, and mixtures thereof.

A further embodiment of any of the foregoing apparatus, wherein theheater assembly comprises a resistance heater disposed within themandrel.

A further embodiment of any of the foregoing apparatus, wherein theheater assembly comprises an energy beam generator disposed adjacent tothe mandrel, the energy beam generator adapted to direct at least oneenergy beam toward the fiber yarn feed track.

A method for making a composite article includes collimating andtensioning a plurality of ceramic monofilaments into a spaced array ofceramic monofilament strands.

The method of the preceding paragraph can optionally include,additionally and/or alternatively, any one or more of the followingfeatures, configurations and/or additional components:

A method according to an exemplary embodiment of this disclosure, amongother possible things, includes the first spaced array of ceramicmonofilament strands commingled with a second array of fiber yarn tows,at least some of which are impregnated with a plurality of glassparticulates. The commingled first array of ceramic monofilament strandsand second array of fiber yarn tows are heated, thereby softening theplurality of glass particulates. The commingled ceramic monofilamentstrands and glass particle impregnated fiber yarn tows are wound onto amandrel. The softened glass particulates, the fiber yarn tows, and themonofilament strands are consolidated into a dual-fiber ceramic matrixcomposite (CMC) material.

A further embodiment of the foregoing method, wherein the consolidationstep is performed at least in part by pressure from the tensioned arrayof monofilament strands acting on the fiber yarn tows and the softenedglass particulates.

A further embodiment of any of the foregoing methods, further comprisingadhering a plurality of glass particulates to form at least some of theplurality of impregnated fiber yarn tows.

A further embodiment of any of the foregoing methods, wherein theadhering step comprises passing at least some of the plurality of fiberyarn tows through a slurry of glass particulates and carrier liquid; andevaporating the carrier liquid from the fiber yarn tows to form theplurality of impregnated fiber yarn tows.

A further embodiment of any of the foregoing methods, wherein the stepof heating the array of fiber yarn tows comprises, prior to the windingstep, directing an energy beam toward the plurality of fiber yarn towsto soften the plurality of glass particulates.

A further embodiment of any of the foregoing methods, wherein the stepof heating the array of fiber yarn tows comprises during the windingstep, heating a surface on or adjacent to the mandrel to soften theplurality of glass particulates.

A further embodiment of any of the foregoing methods, wherein theplurality of ceramic monofilaments comprises a plurality of siliconcarbide (SiC) glass monofilaments.

A further embodiment of any of the foregoing methods, wherein theplurality of glass particulates comprises borosilicate glass particles,lithium aluminosilicate glass particles, barium magnesiumaluminosilicate particles, and mixtures thereof.

A further embodiment of any of the foregoing methods, wherein during atleast one of the winding step and the consolidating step, the pluralityof tensioned monofilament strands apply a pressure of at least about 550MPa (about 80 ksi) to the fiber yarn tows and the softened glassparticulates.

A further embodiment of any of the foregoing methods, wherein a nominaldiameter of each of the ceramic monofilament strands measures at leastabout 100 μm (about 0.0040 inches).

A further embodiment of any of the foregoing methods, wherein a ratio ofceramic monofilament strands to fiber yarn tows is at least about 8:1.

A further embodiment of any of the foregoing methods, wherein the ratioof ceramic monofilament strands to fiber yarn tows is at least about10:1.

Although the present invention has been described with reference topreferred embodiments, workers skilled in the art will recognize thatchanges may be made in form and detail without departing from the spiritand scope of the invention.

1. A method for making a composite article, the method comprising:collimating a plurality of ceramic monofilaments into a first spacedarray of ceramic monofilament strands; tensioning the first spaced arrayof ceramic monofilament strands; commingling the first spaced array ofceramic monofilament strands with a second array of fiber yarn tows, atleast some of the fiber yarn tows impregnated with a plurality of glassparticulates; heating the commingled first array of ceramic monofilamentstrands and second array of fiber yarn tows, thereby softening theplurality of glass particulates; winding the commingled glassmonofilament strands and impregnated fiber yarn tows onto a mandrel; andconsolidating the softened glass particulates, the fiber yarn tows, andthe monofilament strands into a dual-fiber ceramic matrix composite(CMC) material.
 2. The method of claim 1, wherein the consolidation stepis performed at least in part by pressure from the tensioned array ofmonofilament strands acting on the fiber yarn tows and the softenedglass particulates.
 3. The method of claim 1, further comprising:adhering a plurality of glass particulates to form at least some of theplurality of impregnated fiber yarn tows.
 4. The method of claim 1,wherein the adhering step comprises: passing at least some of theplurality of fiber yarn tows through a slurry of glass particulates andcarrier liquid; and evaporating the carrier liquid from the fiber yarntows to form the plurality of impregnated fiber yarn tows.
 5. The methodof claim 1, wherein the step of heating the array of fiber yarn towscomprises: prior to the winding step, directing an energy beam towardthe plurality of fiber yarn tows to soften the plurality of glassparticulates.
 6. The method of claim 1, wherein the step of heating thearray of fiber yarn tows comprises: during the winding step, heating asurface on or adjacent to the mandrel to soften the plurality of glassparticulates.
 7. The method of claim 1, wherein the plurality of ceramicmonofilaments comprises a plurality of silicon carbide (SiC) glassmonofilaments.
 8. The method of claim 1, wherein the plurality of glassparticulates comprises borosilicate glass particles, lithiumaluminosilicate glass particles, barium magnesium aluminosilicateparticles, and mixtures thereof.
 9. The method of claim 1, whereinduring at least one of the winding step and the consolidating step, theplurality of tensioned monofilament strands apply a pressure of at leastabout 430 MPa (about 60 ksi) to the fiber yarn tows and the softenedglass particulates
 10. The method of claim 1, wherein during at leastone of the winding step and the consolidating step, the plurality oftensioned monofilament strands apply a pressure of at least about 570MPa (about 80 ksi) to the fiber yarn tows and the softened glassparticulates.
 11. The method of claim 1, wherein a nominal diameter ofeach of the ceramic monofilament strands measures at least about 100 μm(about 0.0040 inches).
 12. The method of claim 1, wherein a ratio ofceramic monofilament strands to fiber yarn tows is at least about 8:1.13. The method of claim 1, wherein the ratio of ceramic monofilamentstrands to fiber yarn tows is at least about 10:1.